Eyeshield 21 (アイシールド 21, Aishīrudo Nijūichi) is a manga written by Riichiro Inagaki and illustrated by Yusuke Murata. It has been adapted into an anime movie in 2004, an anime television series in 2005, several video games and a trading card game from Konami. The manga was serialized in Shueisha's Weekly Shōnen Jump. The manga is published in English by Viz Media.

The anime version, produced by NAS and animated by Studio Gallop, premiered across Japan on TV Tokyo from April 6, 2005, and ended March 19, 2008 with episode 145. The anime is sponsored by NFL Japan. The English dub aired on the free on-demand Toonami Jetstream as a joint effort with NFL Rush on December 17, 2007, but no more episodes will be dubbed, as the deal with NFL Rush fell through in 2008. It has subsequently been picked up for broadcast on Crunchyroll in a subtitled format. It is also aired in Singapore, Taiwan, Hong Kong, Indonesia, Philippines and South Korea.

The plot of Eyeshield 21 revolves around a weak and non-assertive boy named Sena Kobayakawa who enters the high school of his choice, Deimon Private Senior High School, where his childhood friend Mamori Anezaki attended school the year before. His only remarkable physical abilities are his running speed and intense agility, the result of a school life spent complying with the demands of bullies. It was revealed later that a friend, Riku, taught him how to run fast to help him against bullies. His abilities quickly catch the eye of the high school's American football team captain Yoichi Hiruma, who forces Sena to join the Deimon Devil Bats as its running back.

To protect his identity from recruitment by the other school teams, Sena is forced to publicly assume the role of team manager and enter the field wearing a helmet equipped with a green-tinted eyeshield in order to hide his features under the pseudonym of "Eyeshield 21". The makeshift team initially takes part in the spring football tournament hoping to win with through the strength of their new "secret weapon." However, the extremely weak team is eliminated early on by the Ojo White Knights, a powerhouse football team that focuses on defense.

After Deimon's defeat, the spring tournament is revealed as secondary in importance to the fall tournament, where the teams compete for the chance to play in the "Christmas Bowl", the high school football league championship. Hiruma, Kurita, and Sena regroup and slowly build a real team from other misfits and students looking to define themselves, such as Tarō Raimon, a baseball player who can only catch, and the Ha-Ha Brothers. Other characters slowly join the team, and the series follows the building and growth of the Deimon Devil Bats and its members as well as various rival teams as they all strive to achieve their goal of playing in the Christmas Bowl.